Optical Interferometry Proximity Sensor with Temperature Variation Compensation

ABSTRACT

An optical proximity sensor includes a first vertical cavity surface-emitting laser configured for self-mixing interferometry to determine distance to and/or velocity of an object. The optical proximity sensor also includes a second vertical cavity surface-emitting laser configured for self-mixing interferometry to determine whether any variation in a fixed distance has occurred. The optical proximity sensor leverages output from the second vertical cavity surface-emitting laser to calibrate output from the second vertical cavity surface-emitting laser to eliminate and/or mitigate environmental effects, such as temperature changes.

FIELD

Embodiments described herein relate to optical sensors, and, inparticular, to optical interferometry proximity sensors configured todetermine a distance to, and/or velocity of, an object.

BACKGROUND

An electronic device can include a system or sensor—referred to hereinas a “proximity sensor”—to measure or estimate a distance separatingthat electronic device in free space from an object or surface, such asa user of the electronic device.

However, conventional proximity sensors are often highly susceptible tochanges in temperature. More specifically, thermal expansion orcontraction of a conventional proximity sensor often results in changesto one or more electrical and/or optical properties of the proximitysensor. As such, electronic devices requiring accurate output fromconventional proximity sensors are typically burdened with a requirementto incorporate additional components or systems to compensate foreffects of temperature, thereby increasing design complexity, componentcost, and power consumption.

SUMMARY

Embodiments described herein reference an optical proximity sensorincluding two discrete vertical cavity surface-emitting lasers. Bothvertical cavity surface-emitting lasers are configured for self-mixinginterferometry.

The first vertical cavity surface-emitting laser is configured toilluminate an object to determine a distance to and/or a velocity ofthat object based on self-mixing interferometry. The second verticalcavity surface-emitting laser is configured to illuminate a surface aknown distance away (e.g., an interior surface of a housing enclosingthe optical proximity sensor).

In this manner, the optical proximity sensor leverages output from thesecond vertical cavity surface-emitting laser to calibrate output of thefirst vertical cavity surface-emitting laser. In this manner, calibratedmeasurements obtained from the first vertical cavity surface-emittinglaser are substantially independent of any effects of temperature orother environmental conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to representative embodiments illustrated inthe accompanying figures. It should be understood that the followingdescriptions are not intended to limit this disclosure to one includedembodiment. To the contrary, the disclosure provided herein is intendedto cover alternatives, modifications, and equivalents as may be includedwithin the spirit and scope of the described embodiments, and as definedby the appended claims.

FIG. 1 depicts a schematic representation of an electronic deviceincorporating a proximity sensor, such as described herein, to determinea distance to, and/or a velocity of, an object near the electronicdevice.

FIG. 2A depicts a schematic representation of another electronic deviceincorporating a proximity sensor, such as described herein, to determinea distance to, and/or a velocity of, an object near the electronicdevice.

FIG. 2B depicts a schematic representation of another electronic deviceincorporating a proximity sensor, such as described herein, to determinea distance to, and/or a velocity of, a movable surface of the electronicdevice.

FIG. 3A depicts a schematic representation of an electronic deviceincorporating a proximity sensor, such as described herein, to determinea distance to, and/or a velocity of, a user's finger relative to aninput region of the electronic device.

FIG. 3B depicts a schematic representation of an electronic deviceincorporating a proximity sensor, such as described herein, to determinea distance to, and/or a velocity of, a user's finger relative to atouch-input region of the electronic device.

FIG. 3C depicts a schematic representation of an electronic deviceincorporating a proximity sensor, such as described herein, to determinea distance to, and/or a velocity of, a movable surface of the electronicdevice against which a user of the electronic device can exert a force.

FIG. 3D depicts another schematic representation of an electronic deviceincorporating a proximity sensor, such as described herein, to determinea distance to, and/or a velocity of, a movable surface of the electronicdevice against which a user of the electronic device can exert a force.

FIG. 4 depicts a system diagram of a proximity sensor, such as describedherein.

FIG. 5 depicts a simplified cross section view of a proximity sensor,such as described herein.

FIG. 6 depicts a simplified cross section view of a proximity sensor,such as described herein.

FIG. 7 depicts a simplified cross section view of a proximity sensor,such as described herein.

FIG. 8 depicts a simplified cross section view of a proximity sensor,such as described herein.

FIG. 9 depicts a simplified cross section view of a proximity sensor,such as described herein.

FIG. 10 depicts a simplified cross section view of a proximity sensor,such as described herein.

FIG. 11 is a flowchart depicting example operations of a method ofoperating a proximity sensor, such as described herein.

FIG. 12 is a flowchart depicting example operations of a method ofoperating a proximity sensor, such as described herein.

The use of the same or similar reference numerals in different figuresindicates similar, related, or identical items.

The use of cross-hatching or shading in the accompanying figures isgenerally provided to clarify the boundaries between adjacent elementsand to facilitate legibility of the figures. Accordingly, neither thepresence nor the absence of cross-hatching or shading conveys orindicates any preference or requirement for particular materials,material properties, element proportions, element dimensions,commonalities of similarly illustrated elements, or any othercharacteristic, attribute, or property for any element illustrated inthe accompanying figures.

Similarly, certain accompanying figures include vectors, rays, tracesand/or other visual representations of one or more example paths—whichmay include reflections, refractions, diffractions, and so on, throughone or more mediums—that may be taken by one or more photons originatingfrom one or more light sources shown or, or in some cases, omitted from,the accompanying figures. It is understood that these simplified visualrepresentations of light are provided merely to facilitate anunderstanding of the various embodiments described herein and,accordingly, may not necessarily be presented or illustrated to scale orwith angular precision or accuracy, and, as such, are not intended toindicate any preference or requirement for an illustrated embodiment toreceive, emit, reflect, refract, focus, and/or diffract light at anyparticular illustrated angle, orientation, polarization, color, ordirection, to the exclusion of other embodiments described or referencedherein.

Additionally, it should be understood that the proportions anddimensions (either relative or absolute) of the various features andelements (and collections and groupings thereof) and the boundaries,separations, and positional relationships presented therebetween, areprovided in the accompanying figures merely to facilitate anunderstanding of the various embodiments described herein and,accordingly, may not necessarily be presented or illustrated to scale,and are not intended to indicate any preference or requirement for anillustrated embodiment to the exclusion of embodiments described withreference thereto.

DETAILED DESCRIPTION

Embodiments described herein relate to an optical proximity sensor foran electronic device. These embodiments typically include a verticalcavity surface-emitting laser (“VCSEL”) oriented to radiate a beam oflight toward an object near the optical proximity sensor in order todetermine a distance to that object and/or a velocity of that objectrelative to the optical proximity sensor. A distance to the objectand/or a velocity of the object can be determined based on a reflectionof the radiated beam from an external surface of the object. The objectcan be internal to, or external to, the electronic device incorporatingthe optical proximity sensor. The beam of light may be coherent (e.g.,with all photons having the same frequency and phase) or may have awavelength modulated according to a particular pattern, referred toherein as “wavelength modulation.”

For simplicity of description, example embodiments are understood toreference a VCSEL configured to emit light in a spectral range thatincludes a non-visible frequency band (e.g., infrared or ultravioletlight). However, it may be appreciated that this is merely one exampleand that in other embodiments, more than one VCSEL can be used (e.g., anarray of VCSELs disposed in any suitable pattern) or, additionally oralternatively, one or more VCSELs configured to emit light in a spectralrange including a visible frequency band can be used. Further, althoughnot required for all embodiments, the example VCSEL described inreference to many embodiments that follow is understood to be a Class 1laser as defined by the American National Standards Association; inother cases, higher power lasers may be used.

As noted above, a beam emitted from a VCSEL of an optical proximitysensor may be reflected from an object. At least a portion of thereflected light can be directed back into the VCSEL to return to (i.e.,reenter) a quantum well layer of the VCSEL, interfering with theoperation thereof and changing an electrical property of the VCSEL thechange in the electrical and/or optical property of the VCSEL is relatedto (1) the distance from the optical proximity sensor to the surface ofthe object and (2) the wavelength of light emitted by the VCSEL.

It may be appreciated that, because the wavelength of light emitted bythe VCSEL—whether modulated or fixed—is known, any measured interference(also referred to as “self-mixing”effects) can be correlated to theabsolute distance separating the surface of the object and the opticalproximity sensor, for example by counting interference mode hops or byquantifying a property of a beat frequency (e.g., via frequency domainanalysis). This distance is referred to herein as the “measureddistance” separating the optical proximity sensor and the surface of theobject. As may be appreciated, this construction leverages an effecttypically referred to as “self-mixing” interferometry or reflectometry.

In many embodiments, a second VCSEL can also be used (referred to hereinas an “auxiliary” VCSEL). The auxiliary VCSEL can be positioned near thefirst VCSEL (also referred to herein as the “primary” VCSEL) such thatthe two experience a substantially identical thermal environment. Inthese constructions, the auxiliary VCSEL can be oriented to emit a beamof light toward a surface a fixed and known distance away from theauxiliary VCSEL, such as an internal surface of an enclosure of theoptical proximity sensor. In these examples, a distance measurementobtained from the auxiliary VCSEL can be used to calibrate, insubstantially real time, distance and/or velocity measurements obtainedfrom the primary VCSEL.

These foregoing and other embodiments are discussed below with referenceto FIGS. 1A-12. However, those skilled in the art will readilyappreciate that the detailed description given herein with respect tothese figures is for explanatory purposes only and should not beconstrued as limiting.

FIG. 1 depicts a schematic representation 100 of an electronic device102 configured to measure a distance d to an object 104 and/or avelocity v of the object 104 relative to an optical proximity sensor 106disposed within a housing of the electronic device 102.

The optical proximity sensor 106 can include one or more VCSEL lightsources—including a primary VCSEL light source and an auxiliary VCSELlight source—formed onto a substrate or semiconductor die; forsimplicity of illustration and description the illustrated embodimentomits many of these elements, which are described in greater detail inreference to other figures presented herein.

The VCSEL light source(s) of the optical proximity sensor 106 can beformed in a pattern or array, although this may not be required. TheVCSEL light sources of the optical proximity sensor 106 can be formedfrom any number of suitable materials or combinations of materials. Inone example embodiment, the VCSEL light sources of the optical proximitysensor 106 each include, without limitation or express requirement: afirst distributed Bragg reflector layer; an oxide layer defining anemission aperture; a quantum well layer; a second distributed Braggreflector layer; and so on. In other examples, additional or fewerlayers may be required. For simplicity of description, two VCSEL lightsources of the optical proximity sensor 106 are referenced below—aprimary VCSEL light source configured to emit light toward the object104 and an auxiliary VCSEL light source configured to emit light towarda surface (not shown) a fixed distance away from the auxiliary VCSELlight source.

In many cases, the primary VCSEL light source and the auxiliary VCSELlight source of the optical proximity sensor 106 are each disposedwithin the same protective enclosure, potting, or encapsulation(including any housing or enclosure of the electronic device 102) toprevent damage.

As noted above, the primary VCSEL light source of the optical proximitysensor 106 can be used to determine a distance d to and/or a velocity vof the object 104. For example, in one embodiment, wavelength modulationmay be used by the optical proximity sensor 106 to simultaneously detectdistance d to, and velocity v of, the object 104 relative to the opticalproximity sensor 106. Wavelength modulation can be achieved bymodulating a drive current supplied to the VCSEL.

One example wavelength modulation leverages a triangular waveformincluding an “up cycle” (in which current supplied to the primary VCSELand, correspondingly, wavelength of the radiated beam emitted therefromincrease linearly at a particular rate) and a “down cycle” (in whichcurrent supplied to the primary VCSEL and wavelength of the radiatedbeam emitted therefrom decrease linearly at the same particular rate).In this example, the undulation in wavelength can effectively simulatemotion of the object 104 toward and away from the optical proximitysensor 106, whether or not that object 104 is actually moving. In theseexamples, frequency content of power output from the primaryVCSEL—affected by self-mixing interference effects—can be described byEquation 1, presented below.

More specifically, in Equation 1 (below), the quantity f_(t) denotes afrequency at which power output from the primary VCSEL of the opticalproximity sensor 106 is modulated at a particular time t when theprimary VCSEL of the optical proximity sensor 106 is emitting light at awavelength λ.

It may be appreciated that as the absolute distance d to the objectchanges (which is equal to half of the total round-trip distance,d_(rt)), light received by the primary VCSEL at time t will have adifferent wavelength than the light emitted by the primary VCSEL at thesame time t because the wavelengths of the two beams differ by an amountrelated to the rate of change over time in wavelength

$\frac{d\; \lambda}{dt}$

multiplied by the total round-trip flight time required for thepreviously-emitted light to traverse the round-trip distance d_(rt) fromthe primary VCSEL to the object and back.

In this manner, power output from the primary VCSEL follows thetriangular waveform (e.g., a current injected into the VCSEL lightsource at a rate of

$\left. \frac{dI}{dt} \right).$

In addition, power output from the primary VCSEL has an interferencesignal superimposed upon that triangular waveform that corresponds tothe effects of constructive or destructive interference that resultsfrom different wavelengths of light interfering with one another inspecific ways.

More specifically, the superimposed interference corresponds to thenumber of constructive and destructive interference “mode” transitions(e.g., also referred to as a beat frequency) that occur between twospecific wavelengths of light that are determined based on the absolutedistance to—or, more specifically, the round-trip time required totravel to and from—the object and based on the rate of change inwavelength

$\frac{d\; \lambda}{dt}$

which, in turn, is based on the rate of change in current injected intothe VCSEL light source

$\frac{d\; \lambda}{dt}.$

Phrased in another manner, a wavelength of light emitted from theprimary VCSEL at time t₀ is different from a wavelength of light emittedfrom the primary VCSEL at time t₁ by an amount determined by the rate ofchange in wavelength

$\frac{d\; \lambda}{dt}.$

In this manner, because different wavelengths of light are emitted atdifferent times (based on the rate of change

$\left. \frac{d\; \lambda}{dt} \right),$

different wavelengths of light will be received at within the primaryVCSEL based on the time at which that particular wavelength was emitted.

As such, generally and broadly, it may be appreciated that the frequencycontent of the power output from the primary VCSEL (e.g., quantityf_(t)) is directly related to the absolute distance separating theprimary VCSEL and the object 104. The auxiliary VCSEL may operate on thesame principle.

Further, it may be appreciated that, quantity f_(t) may increase ordecrease as a result of one or more Doppler effects resulting from thevelocity v of the object 104. For example, if the object 104 is movingtoward the optical proximity sensor (e.g., parallel to the direction ofpropagation of the emitted beam), the frequency f_(t) may increase.Alternatively, if the object 104 is moving away from the opticalproximity sensor (e.g., parallel to the direction of propagation of theemitted beam), the frequency f_(t) may decrease.

Equation 1, relating the values referenced above, follows:

$\begin{matrix}{f_{t} = {{\frac{d\; \lambda}{dt} \cdot \frac{d_{rt}}{\lambda^{2}}} \pm \frac{2v}{\lambda}}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In a more general form, the direction of motion of the object 104—ormore particularly, the angle θ of motion of the object 104 relative tothe direction of propagation of the emitted beam—can also be considered.Equation 2, representing this more general form, follows:

$\begin{matrix}{f_{t} = {{\frac{d\; \lambda}{dt} \cdot \frac{d_{rt}}{\lambda^{2}}} \pm {\frac{2v}{\lambda}{\cos (\theta)}}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

Using either Equation 1 or Equation 2, it may be appreciated that thedistance to the object 104, represented by

$\frac{d_{rt}}{2},$

and the velocity of that object 104 v, can be readily determined bymonitoring one or more characteristics of the frequency content of thepower consumed by the primary VCSEL during the up cycle and down cycleof a triangular modulation waveform. As described in reference tocertain embodiments that follow, these measurements obtained from theprimary VCSEL can be calibrated, adjusted, or otherwise modified inresponse to a similar measurement obtained from the auxiliary VCSEL.

In many embodiments, the optical proximity sensor 106 is configured toleverage triangular waveform modulation to obtain both distance andvelocity information from a VCSEL (or array of VCSELs), such as theprimary VCSEL, although it may be appreciated that this is merely oneexample and that other constructions and modulation techniques may beused.

Notwithstanding the foregoing, it may be appreciated that environmentalconditions such as temperature and/or barometric pressure can affect oneor more electrical properties of the primary VCSEL which, in turn, candecrease accuracy or precision of any calculation(s) based thereon(e.g., determinations of an object's distance, velocity, acceleration,and so on).

For example, as temperature or pressure changes, mechanical expansion orcontraction may change physical proportions of a Bragg reflector and/ora quantum well layer of the primary VCSEL, which in turn may result in achange in the wavelength or modulation of light emitted from thatprimary VCSEL. In another example, as temperature changes, electricalresistance of the primary VCSEL will likewise change, decreasing thereliability of any measurements or operations that may be based on, ormay require, precise voltage, current, or resistance. In still furthercases, as temperature or pressure changes refractive index(es) of one ormore portions of the primary VCSEL, which in turn may result in a changein the wavelength of light emitted from the primary VCSEL.

Accordingly, and as noted above, the optical proximity sensor 106 alsoincludes the auxiliary VCSEL, which is positioned next to (e.g., on thesame die or substrate), and typically but not necessarily constructed inthe same manner as, the primary VCSEL. In many embodiments, theauxiliary VCSEL is thermally coupled to the primary VCSEL via a thermalcoupling such that the primary VCSEL and the auxiliary VCSEL experiencethe same thermal environment.

More broadly, as a result of the physical proximity, thermal coupling,and/or similar (or identical) construction, it may be appreciated thatthe primary VCSEL and the auxiliary VCSEL in these constructionsexperience substantially identical environmental conditions.

In certain of these embodiments, the auxiliary VCSEL of the opticalproximity sensor 106 is oriented to radiate a coherent beam of lighttoward a fixed reflective surface near, or within, the optical proximitysensor 106 (not shown). In many examples, the reflective surface isdisposed substantially perpendicular to a propagation direction of thatbeam. The reflective surface is separated from the auxiliary VCSEL by afixed and known distance referred to herein as the “reference distance.”

In these examples, the beam radiated from the auxiliary VCSEL (which istypically modulated in the same manner as the primary VCSEL) reflectsfrom the reflective surface, resulting in self-mixing interference. Aswith the primary VCSEL, the self-mixing interference effects experiencedby the auxiliary VCSEL correspond to (1) the reference distance and (2)the wavelength or modulation of light emitted by the auxiliary VCSEL. Itmay be appreciated that because both of these values are known, theself-mixing interference effects experienced by the auxiliary VCSEL aresubstantially constant while environmental conditions of the opticalproximity sensor remain the same.

As a result of this example construction, self-mixing effectsexperienced by the auxiliary VCSEL can be leveraged as a reference tocancel or mitigate effects of environmental conditions, on the primaryVCSEL, such as changes in temperature or barometric pressure.

In view of the foregoing, more generally and broadly, embodimentsdescribed herein relate to an optical proximity sensor—such as theoptical proximity sensor 106—that leverages self-mixing interferometryto: (1) measure a variable distance and/or velocity to a surface orobject; and (2) to measure variances or changes, if any, in a referencedistance. Thereafter, the optical proximity sensor or, morespecifically, a processing unit, circuit, or other controller of theoptical proximity sensor, adjusts the measured variable distance inproportion to a variance detected in the reference distance. Moresimply, an optical proximity sensor, such as described herein, uses ameasurement of a reference distance to calibrate—in realtime—measurements of a variable distance. This construction has theeffect, in many embodiments, of substantially reducing variability dueto environmental conditions, such as temperature.

Any stationary or portable electronic device can incorporate an opticalproximity sensor, such as described herein. Example electronic devicesinclude, but are not limited to: mobile phone devices; tablet devices;laptop devices; desktop computers; computing accessories; peripheralinput devices; home or business networking devices; aerial, marine,submarine, or terrestrial vehicle control devices or networking devices;mobile entertainment devices; augmented reality devices; virtual realitydevices; industrial control devices; digital wallet devices; home orbusiness security devices; wearable devices; head-mounted devices;hand-held controllers; health or medical devices; implantable devices;clothing-embedded devices; fashion accessory devices; home or industrialappliances; media appliances; and so on.

Similarly, the optical proximity sensor 106 can be leveraged by anelectronic device for a number of suitable purposes. Example purposesinclude, but are not limited to: detecting distance and velocity of auser's finger (or other object, such as a stylus) to an input surface orcomponent of the electronic device; detecting distance and velocity of auser's body (or any other object) to an input surface or component ofthe electronic device; detecting deflection in a surface of a housing ofthe electronic device due to a deformation caused by an application offorce (e.g., by a user or other object, such as a stylus); and the like.

Similarly, the optical proximity sensor 106 can be manufactured orconstructed in a number of suitable ways. Examples include, but are notlimited to: a primary VCSEL positioned on the same die as an auxiliaryVCSEL and disposed within an opaque enclosure defining a singletransparent aperture aligned above the primary VCSEL; a primary VCSELpositioned on the same die as an auxiliary VCSEL and disposed within atransparent enclosure having a reflective material disposed above theauxiliary VCSEL; a single VCSEL disposed within an enclosure having apartially reflective material disposed above the VCSEL; and the like.

Similarly, the optical proximity sensor 106 can include any number ofsuitable optical adapters, lenses, or beam-shaping elements. Examplesinclude, but are not limited to: reflectors; mirrors; translucent lenswindows; transparent lens windows; concave lenses; convex lenses; tiltedlenses; microlenses; macro lenses; collimators; polarizers; colorfilters; infrared-cut filters; infrared-pass filters; fiber opticcables; and the like.

In many embodiments, the optical proximity sensor 106 includes acomponent enclosure formed from a plastic or acrylic material; otherconductive or non-conductive/insulating materials including glass andmetal may also be suitable. The component enclosure can be formed from asingle material or, alternatively, can be formed from multiple layers orregions of different materials joined together in a suitable manner(e.g., by adhesive, welding, and the like).

The component enclosure of the optical proximity sensor 106 can beopaque or transparent, or may include transparent regions and opaqueregions. The component enclosure can include one or more reflectiveareas or regions.

In many embodiments, the component enclosure includes a lens or windowdisposed in an aperture defined through, or formed within, the componentenclosure. Typically, the lens or window is disposed directly above, andaligned with, at least one of the VCSEL light sources. As a result ofthis construction, a beam of light emitted/radiated from at least one ofthe VCSEL light sources can propagate outwardly from the componentenclosure of the optical proximity sensor 106. As an additional resultof this construction, one or more reflections of an emitted/radiatedbeam that may reflect from a surface of the object 104 can be receivedby at least one of the VCSEL light sources.

In many embodiments, the optical proximity sensor 106 also includes oneor more photodiodes disposed adjacent to, or integrated in, each of theVCSEL light sources. In these examples, the optical proximity sensor 106(or, more specifically, a circuit or processor of, or communicablycoupled to, the optical proximity sensor 106) can monitor power outputfrom a photodiode to determine one or more performance characteristics,such as modulation frequency of that power output of a particular VCSELlight source. (see, e.g., Equations 1-2). It may be appreciated,however, that this foregoing example is merely one example; monitoringand/or measuring power output by and/or power consumption of a VCSELlight source may be performed in a number of suitable ways.

In some embodiments, the optical proximity sensor 106 includes a thermalmass coupled to each VCSEL of the VCSEL light sources to promote eventemperature distribution between each VCSEL light source. In othercases, a thermally conductive layer can be disposed adjacent to or beloweach VCSEL light source.

In one specific implementation of the example introduced above, theoptical proximity sensor 106 of the electronic device 102 includes acomponent enclosure that retains, encloses, and protects two VCSEL lightsources. For this embodiment, a first VCSEL light source is referred toas the primary VCSEL and a second VCSEL light source is referred to asthe auxiliary VCSEL light source.

As with other embodiments described herein, the primary VCSEL lightsource can be configured to emit a beam of laser light outwardly fromthe component enclosure of the optical proximity sensor 106. In theillustrated embodiment, the primary VCSEL light source is oriented toemit/radiate light in a direction generally perpendicular to an edge ofa housing of the electronic device 102. It may be appreciated, however,that this is merely one example and that other emission or radiationdirections are possible. (see, e.g., FIG. 2A)

As with other embodiments described herein, the primary VCSEL lightsource is further configured to receive a reflection of theemitted/radiated beam off the object 104. This reflection can result inself-mixing interference within the primary VCSEL light source which, inturn, can affect power output of the primary VCSEL light source.Accordingly, monitoring power output of the primary VCSEL light source(e.g., via monitoring an output of a photodiode, such as describedabove) can be used to determine and/or calculate the distance d and thevelocity v of the object 104 relative to the electronic device 102.(see, e.g., Equations 1-2).

Also as with other embodiments described herein, the auxiliary VCSELlight source can be configured to emit a beam of light toward areflective surface separated from the auxiliary VCSEL light source by afixed reference distance.

In some cases, the reflective surface is an interior surface of thecomponent enclosure of the optical proximity sensor 106. In other cases,the reflective surface is an exterior surface of the component enclosureof the optical proximity sensor 106. In yet other examples, thereflective surface is defined by a reflective or metallic materialdisposed onto (e.g., via physical vapor deposition or another suitabletechnique), or molded within (e.g., via insert molding or co-molding), asurface or body portion of the component enclosure of the opticalproximity sensor 106.

As with other embodiments described herein, the auxiliary VCSEL lightsource is further configured to receive a reflection of the beam emittedtherefrom off the reflective surface. This reflection can result inself-mixing interference within the auxiliary VCSEL light source which,in turn, can affect power consumption by and/or power output of theauxiliary VCSEL light source. As with the primary VCSEL light source aphotodiode may be used to monitor power output by and/or powerconsumption of the auxiliary VCSEL light source which, in turn, can beused to determine and/or calculate a variation in the referencedistance—if any. (see, e.g., Equations 1-2). Any detected or calculatedvariance in the reference distance can be used to calibrate, in realtime, the output of the primary VCSEL light source.

The optical proximity sensor 106 and the electronic device 102 can becommunicably or functionally coupled in any suitable manner. Morespecifically, the optical proximity sensor 106 can be configured tocommunicate distance and/or velocity information (which is calculated orotherwise determined based on self-mixing of the primary VCSEL lightsource calibrated based on self-mixing of the auxiliary VCSEL lightsource), to a processor or system of the electronic device 102 in anysuitable manner, according to any protocol, in compliance with anysuitable digital or analog form or format.

Furthermore, as noted above, the electronic device 102 can be anysuitable electronic device including both stationary and portableelectronic devices. In one embodiment, the electronic device 102 is awearable electronic device, such as a smart watch. In this example, theelectronic device 102 can leverage the optical proximity sensor 106 todetermine a distance to a user (represented by the object 104) and avelocity of that user while that user is interacting with the electronicdevice 102. For example, the electronic device 102 can leverage a signalsent from the optical proximity sensor 106 to determine whether a useris wearing the smart watch or is directing the smart watch toward theuser's face.

More specifically, in some embodiments, the electronic device 102 may beconfigured to perform a function upon determining that the user has tocross one or more thresholds, such as distance thresholds or velocitythresholds. Such thresholds may be variable or fixed and may be set by,and/or stored within, a memory of the electronic device 102. In someexamples, the thresholds may be based on a user setting, an applicationsetting, or an operating system setting or mode of operation. In othercases, such thresholds may be based, at least in part, on a particularapplication executed or instantiated by a processor of the electronicdevice 102. For example, a threshold set associated with a telephonyapplication may be different from a threshold set associated with agaming application. It may be appreciated that any suitable threshold orset of thresholds, stored or accessed in any suitable form or format maybe used to inform one or more behaviors of the electronic device 102 inresponse to a signal received from the optical proximity sensor 106.

In one specific embodiment, the electronic device 102 can disable ascreen of the electronic device 102 upon determining that a user is afar distance away from the electronic device 102.

In another specific embodiment, the electronic device 102 can modify adisplay or power setting of the electronic device 102 based on thedistance and velocity of the user. Examples include, but may not belimited to: decreasing a brightness of a display or a display regionupon receiving a signal from the optical proximity sensor 106 that theuser is covering the display; increasing a brightness of a display uponreceiving a signal from the optical proximity sensor 106 that the useris covering the display; highlighting a user interface element (e.g., anitem of a list, a button, and the like) of a graphical user interfaceupon receiving a signal from the optical proximity sensor 106 that theuser is hovering a finger near the display; highlighting or otherwisemodifying a user interface element of a graphical user interface uponreceiving a signal from the optical proximity sensor 106 that the useris hovering a finger near an input component of the electronic device102 (e.g., rotary input device, push-button input device, touch inputdevice, and so on); and so on.

In another embodiment, the electronic device 102 may be a portableelectronic device such as a cellular phone. In these examples, theelectronic device 102 can leverage a velocity or distance signalreceived from the optical proximity sensor 106 to determine anappropriate time to disable or enable a touch-sensitive display of theelectronic device 102 when a user of the electronic device raises thecellular phone to the user's ear.

In another embodiment, the electronic device 102 may leverage a velocityor distance signal received from the optical proximity sensor 106 todetermine whether the electronic device 102 is falling or willimminently impact a surface.

In another embodiment, the electronic device 102 may be a vehicleaccessory or attachment. In these examples, the electronic device 102can leverage a velocity or distance signal received from the opticalproximity sensor 106 to determine a distance to, and/or a velocity of,another vehicle, pedestrian, or a road hazard.

In another embodiment, the electronic device 102 may position an opticalproximity sensor, such as the optical proximity sensor 106, within aninput/output communication port or a power port of the electronic device102. In these examples, the electronic device 102 can leverage avelocity or distance signal received from the optical proximity sensor106 to determine whether a cable is properly seated in the port, whethera cable is removed too quickly or in a manner that may cause damage tothe electronic device 102, and so on.

It may be appreciated that the foregoing example embodiments are notexhaustive and that an optical proximity sensor, such as describedherein, can be leveraged by an electronic device in any suitable mannerto determine distance and/or velocity of a known or unknown object orsurface relative to the electronic device.

For example, in some embodiments, an electronic device can include morethan one optical proximity sensors, such as described herein. In anotherexample, an electronic device can include an array of optical proximitysensors arranged in a pattern, such as in a line.

In many cases, an optical proximity sensor, such as described herein,can be disposed within a housing of an electronic device and alignedwith a transparent aperture defined by the housing, but this may not berequired. For example, in some embodiments, an optical proximity sensorcan be disposed behind a display. In other cases, an optical proximitysensor can be disposed entirely within an electronic device housing. Inthese examples, the optical proximity sensor can be used to detectdeflections or deformations in a surface of the electronic device thatcan result from a user applying a purposeful force to that surface. Forexample, in one embodiment, an optical proximity sensor is positionedentirely within a housing of an electronic device, behind a display. Inthis example, when a user of the electronic device applies a force tothe display, the display may deform or bend, shortening the distancebetween the display and the optical proximity sensor. The opticalproximity sensor, in turn, can detect and measure this deflection whichcan be correlated by a processor of the electronic device—and/or aprocessor of the optical proximity sensor—into a magnitude of forceinput.

The foregoing examples are not exhaustive; it may be appreciated thatgenerally and broadly an electronic device can leverage one or moreoptical proximity sensors, such as described herein, for any suitablepurpose or function.

For example, FIG. 2A depicts a schematic representation 200 a of anelectronic device 202 configured to measure a distance d to an object204 and/or a velocity of the object 204 relative to an optical proximitysensor 206, such as described herein. In this example embodiment, theoptical proximity sensor 206 can include a beam-shaping lens thatredirects light emitted from the optical proximity sensor 206 to anangle θ. In this manner and as a result of this construction, theelectronic device 202 and the optical proximity sensor 206 can determinevelocity in multiple directions or along multiple axes (e.g., v_(x) andv_(y)). In this manner, together (optionally) with one or moreadditional optical proximity sensors, the electronic device 202 candetermine multi-axis velocity and distance.

Still other embodiments can be implemented in other manners. Forexample, FIG. 2B depicts a schematic representation 200 b of anelectronic device 202 configured to leverage an optical proximity sensor206 to measure a distance d to a flexible surface 208 and a velocity vof one or more deformations or flexions of that flexible surface 208. Inthis manner, and as a result of this construction, flexion of theflexible surface 208 can be quantified by the electronic device 202.

The foregoing embodiment depicted in FIGS. 1-2B and the variousalternatives thereof and variations thereto are presented, generally,for purposes of explanation, and to facilitate an understanding ofvarious configurations and constructions of an optical proximity sensor,such as described herein. However, it will be apparent to one skilled inthe art that some of the specific details presented herein may not berequired in order to practice a particular described embodiment, or anequivalent thereof.

Thus, it is understood that the foregoing and following descriptions ofspecific embodiments are presented for the limited purposes ofillustration and description. These descriptions are not targeted to beexhaustive or to limit the disclosure to the precise forms recitedherein. To the contrary, it will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings.

For example, as noted above, an optical proximity sensor such asdescribed herein, can be leveraged by an electronic device for, withoutlimitation: determining a proximity of a user to the electronic devicebeyond a threshold; determining a distance separating a user and theelectronic device; determining a distance separating a user's finger andthe electronic device; determining a distance separating a user's fingerand an input region (e.g., touch screen, force input sensor, physicalinput component, rotary input component) of the electronic device;determining a velocity with which a user's finger approaches theelectronic device; determining a velocity or distance with which asurface of the electronic device deforms or deflects in response to aninput force; a velocity or distance with which a housing portion of theelectronic device deforms or deflects in response to an input force; andso on.

Expanding upon these and related examples, FIGS. 3A-3D are presented todepict various example use cases for an optical proximity sensor, suchas described herein. These figures depict a wearable electronic device,such as a smart watch, but it may be appreciated that this is merely oneexample. An optical proximity sensor, such as described herein, can beincorporated into any suitable electronic device and leveraged for anysuitable purpose.

For example, FIG. 3A depicts a wearable electronic device 300 includinga housing 302 that can be worn by a user (e.g., via a wristband 304). Inthis example, an optical proximity sensor 306 can be included within thehousing 302 and positioned relative to a periphery or bezel region of adisplay 308 that defines a graphical user interface 308 a with which auser can interact. As a result of this construction, the opticalproximity sensor 306 can be configured to and oriented to detect,measure, or otherwise determine a distance d and/or a velocity v of auser's finger 310 relative to an input component 312. The inputcomponent 312 can be any suitable input component including, but notlimited to: a rotating input component (e.g., a crown); a press-buttoninput component; a solid-state input component; and so on.

In this example embodiment, the wearable electronic device 300 can beconfigured to perform a first function upon determining that the user'sfinger 310 is approaching the input component 312, to perform a secondfunction upon determining that the user's finger 310 is departing ormoving away from the input component 312, to perform a third functionupon determining that the user's finger 310 is hovering near or on theinput component 312, and so on. It may be appreciated that theseexamples are not exhaustive and that the wearable electronic device 300can perform any suitable function or operation based on the distance dand/or the velocity v of the user's finger 310 relative to the inputcomponent 312 as determined by the optical proximity sensor.

For example, in one embodiment, the wearable electronic device 300 canmodify a position, characteristic, size, color, or other quality of agraphical user interface element 308 b in response to a change in thedistance d between the input component 312 and the user's finger 310.

In another example, FIG. 3B depicts a wearable electronic device 300including a housing 302 configured to couple to a user via a wristband304. An optical proximity sensor 306, such as described herein, can bedisposed behind a display 308 that renders a graphical user interface308 a. In one example, the optical proximity sensor 306 is configured toemit light through an inter-pixel region of the display 308.

In this example, the optical proximity sensor 306 can be configured toand oriented to detect, measure, or otherwise determine a distance dand/or a velocity v of a user's finger 310 relative to the display 308and/or to the graphical user interface 308 a. The display 308 can beimplemented as or with, without limitation: a touch-sensitive screen ordisplay; a force-sensitive screen or display; a haptic-output surface;and so on.

In this example embodiment, as with other embodiments described herein,the wearable electronic device 300 can be configured to perform anysuitable function or operation based on the distance d and/or thevelocity v—and/or changes therein over time—of the user's finger 310relative to the display 308 as determined by the optical proximitysensor.

In another example, FIG. 3C depicts a wearable electronic device 300including a housing 302 that can be attached to a user via a wristband304. An optical proximity sensor, such as described herein, can bedisposed within the housing 302. In this example, the optical proximitysensor can be configured to and oriented to detect, measure, orotherwise determine a distance d and/or a velocity v of a deflection ofa display 308 that results from a downward force applied by the user'sfinger 310 to a graphical user interface 308 a rendered by the display308. The display 308 can be configured in the same manner as describedin reference to FIG. 3B, and this description is not repeated.

In this example embodiment, as with other embodiments described herein,the wearable electronic device 300 can be configured to perform anysuitable function or operation based on the distance d and/or thevelocity v—and/or changes therein over time—of the user's finger 310relative to the display 308 as determined by the optical proximitysensor. In many examples, the wearable electronic device 300 can beconfigured to correlate or otherwise convert at least one of a distanced and/or a velocity v of the deflection of an display 308 into amagnitude of force input F.

In yet another example, FIG. 3D depicts a wearable electronic device 300including a housing 302 that can be attached to a user via a wristband304. An optical proximity sensor 306, such as described herein, can bedisposed within the housing 302 adjacent to a sidewall of the housing302. More specifically, in this example, the optical proximity sensor306 can be configured to and oriented to detect, measure, or otherwisedetermine a distance d and/or a velocity v of a deflection of a housingsidewall or housing section—identified in the figure as the sidewall 310that results from a force F applied by the user 304.

In this example embodiment, as with other embodiments described herein,the wearable electronic device 300 can be configured to perform anysuitable function or operation based on the determine magnitude of theforce F—and/or changes therein over time—applied by the user's finger310 as determined by the optical proximity sensor.

The foregoing embodiment depicted in FIGS. 3A-3D and the variousalternatives thereof and variations thereto are presented, generally,for purposes of explanation, and to facilitate an understanding ofvarious possible means by which an optical proximity sensor, such asdescribed herein, can be leveraged or otherwise used by an electronicdevice. However, it will be apparent to one skilled in the art that someof the specific details presented herein may not be required in order topractice a particular described embodiment, or an equivalent thereof.

Thus, it is understood that the foregoing and following descriptions ofspecific embodiments are presented for the limited purposes ofillustration and description. These descriptions are not targeted to beexhaustive or to limit the disclosure to the precise forms recitedherein. To the contrary, it will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings.

For example, it may be appreciated that, generally and broadly, and inview of the foregoing examples, an optical proximity sensor, such asdescribed herein, can be used in a number of suitable ways to detectdistance and/or velocity of any suitable surface. FIG. 4 depicts asystem diagram of an optical proximity sensor 400, such as describedherein. In particular, the optical proximity sensor 400 includes aprocessor 402, a memory 404 (optional), and a power controller 406 eachof which may be interconnected and/or communicably or conductivelycoupled in any suitable manner.

As described herein, the term “processor” refers to any software and/orhardware-implemented data processing device or circuit physically and/orstructurally configured to instantiate one or more classes or objectsthat are purpose-configured to perform specific transformations of dataincluding operations represented as code and/or instructions included ina program that can be stored within, and accessed from, a memory, suchas the memory 404. This term is meant to encompass a single processor orprocessing unit, multiple processors, multiple processing units, analogor digital circuits, application-specific integrated circuits, or othersuitably configured computing element or combination of elements.

The power controller 406 is coupled to a primary VCSEL light source 408and an auxiliary VCSEL light source 410. Each of these components—alongwith other components of the optical proximity sensor 400 that may berequired or preferred in particular embodiments or implementations—canbe disposed in whole or in part within a component enclosure 412. Theoptical proximity sensor 400 also includes a window 414 configured toallow light emitted from the primary VCSEL light source 408 to passthrough the component enclosure 412 to illuminate a surface of an object416.

In these examples, the processor 402 can be configured to cause thepower controller 406 to generate a triangular current waveform (or othersuitable periodic or non-periodic waveform) to simultaneously injectcurrent into the primary VCSEL light source 408 and the auxiliary VCSELlight source 410. As noted with respect to other embodiments describedherein, the primary VCSEL light source 408 and the auxiliary VCSEL lightsource 410 can each be configured to operate in a manner that leverageseffects of self-mixing.

For simplicity, the operation of injecting current, whether modulated orotherwise, into a VCSEL light source to emit light and to promotingself-mixing, whether by a power controller or processor such asdescribed herein, is referred to herein as “driving” a light source.

In the illustrated embodiment, the primary VCSEL light source 408 isaligned with the window 414 such that light emitted from the primaryVCSEL light source 408 traverses the window 414 and illuminates asurface of the object 416 (which may be a user, an internal surface ofan electronic device, and so on).

Reflections from the object 416 traverse the window 414 and reenter theprimary VCSEL light source 408 to cause self-mixing interference that isdirectly related to the distance d_(var) separating the object 416 fromthe primary VCSEL light source 408 and, additionally directly related tothe velocity of the object 416 relative to the primary VCSEL lightsource 408. In some cases, the power controller 406 can be furtherconfigured to monitor power output from one or more photodiodesoptically coupled to the primary VCSEL light source 408 in order toquantify and/or otherwise determine variations in power output of theprimary VCSEL light source 408 that result from the self-mixing effects.(see, e.g., Equations 1-2).

Conversely, in the illustrated embodiment, the auxiliary VCSEL lightsource 410 is positioned within the component enclosure 412 such thatlight emitted from the auxiliary VCSEL light source 410 only illuminatesan internal surface of the component enclosure 412.

Reflections from the internal surface of the component enclosure 412reenter the auxiliary VCSEL light source 410 to cause self-mixinginterference that is directly related to the distance d_(ref) separatingthe internal surface of the component enclosure 412 from the auxiliaryVCSEL light source 410. In some cases, as with the primary VCSEL lightsource 408 described above, the power controller 406 can be furtherconfigured to monitor power output from one or more photodiodesoptically coupled to the auxiliary VCSEL light source 410 in order toquantify and/or otherwise determine variations in power output of theauxiliary VCSEL light source 410 that result from the self-mixingeffects. (see, e.g., Equations 1-2).

In these embodiments, the processor 402 can be configured to receive oneor more signals from the power controller 406 that correspond to one ormore power use and/or power output characteristics of the auxiliaryVCSEL light source 410 and the primary VCSEL light source 408.Thereafter, the processor 402 can be configured to calibrate and/orotherwise adjust an output corresponding to the primary VCSEL lightsource 408 based on an output corresponding to the auxiliary VCSEL lightsource 410 that relates to the fixed reference distance d_(ref).

It may be appreciated that the calibration operation described hereincan be performed by the processor 402 at any suitable time with anysuitable form or format of data output from the power controller 406.For example, in some implementations, the processor 402 can beconfigured to modify or calibrate raw power consumption data—whetherdigital or analog—corresponding to the primary VCSEL light source 408whereas in other cases, the processor 402 can be configured to modify orcalibrate distance or velocity calculations. In still further examples,more than one calibration operation can be performed in sequence or inparallel on any suitable data.

In this manner, and a result of the foregoing described example systemarchitecture, an optical proximity sensor, such as described herein, isgenerally and broadly configured to (1) determine in real time orsubstantially real time a distance and/or velocity calculation based onself-mixing interferometry and (2) to calibrate those measurements basedon a second self-mixing interferometry calculation that is based on afixed, reference distance.

More broadly, these foregoing embodiments depicted in FIGS. 3A-3D andthe various alternatives thereof and variations thereto are presented,generally, for purposes of explanation, and to facilitate anunderstanding of various optical proximity sensor system architectures,such as described herein. However, it will be apparent to one skilled inthe art that some of the specific details presented herein may not berequired in order to practice a particular described embodiment, or anequivalent thereof.

Thus, it is understood that the foregoing and following descriptions ofspecific embodiments are presented for the limited purposes ofillustration and description. These descriptions are not targeted to beexhaustive or to limit the disclosure to the precise forms recitedherein. To the contrary, it will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings.

For example, it may be appreciated that an optical proximity sensor and,in particular, a primary and auxiliary VCSEL associated therewith can bearranged and constructed in a variety of ways. As such, FIGS. 5-10 arepresented to illustrate various example embodiments of an opticalproximity sensor, such as described herein.

In particular, FIG. 5 depicts a simplified cross section view of anoptical proximity sensor 500, such as described herein. The opticalproximity sensor 500 is formed, at least in part, on a substrate 502 towhich a semiconductor die 504 can be conductively and mechanicallycoupled. The semiconductor die 504 includes two separate VCSEL regions,each of which can include one or more individual VCSELs. These regionsare identified in the figure as the auxiliary VCSEL region 506 and theprimary VCSEL region 508. As noted with respect to other embodimentsdescribed herein, the auxiliary VCSEL region 506 and the primary VCSELregion 508 may be physically proximate (or immediately adjacent) to oneanother specifically such that each experiences substantially the sameenvironmental conditions (e.g., temperature).

The semiconductor die 504, in addition to the auxiliary VCSEL region 506and the primary VCSEL region 508 are enclosed on the substrate 502 by acomponent enclosure 510. An optical adapter 512 is insert molded orotherwise disposed into the component enclosure 510 and aligned above acentral region or emission axis of the primary VCSEL region 508. In manyexamples, the optical adapter 512 may serve as a lens, but this is notrequired.

As a result of this construction, a beam of light emitted from theprimary VCSEL region 508 can traverse the optical adapter 512 toilluminate an object 514. As with other embodiments described herein, aportion of the light radiated/emitted from the primary VCSEL region 508can reflect from the object 514 and return to the primary VCSEL region508 to facilitate self-mixing interferometry detection and/ormeasurement of a distance d_(var) (and/or a velocity v) that separatesan exterior surface of the component enclosure 510 from the surface ofthe object 514.

Conversely, a beam of light emitted from the auxiliary VCSEL region 506does not traverse the optical adapter 512 and, instead, reflectsdirectly from an interior surface of the component enclosure 510 tofacilitate self-mixing interferometry detection and/or measurement of afixed reference distance d_(ref).

As noted with respect to other embodiments described herein,interferometric calculations and/or measurements to cancel or mitigateeffects of temperature and/or other environmental conditions can beperformed in whole or in part by a power controller 516 coupled to theprimary VCSEL region 508 and the auxiliary VCSEL region 506. The powercontroller 516 may be configured in the same manner as described abovein reference to FIG. 4; this description is not repeated.

In this example embodiment, the component enclosure 510 may besubstantially opaque, although this may not be required. Similarly, inthis example, the optical adapter 512 may be insert molded or otherwiseformed from a separate material from the component enclosure 510; thisis also not expressly required.

For example, FIG. 6 depicts a simplified cross section view of anoptical proximity sensor 600, such as described herein. As with otherembodiments described herein, the optical proximity sensor 600 isformed, at least in part, on a substrate 602 to which a semiconductordie 604 can be conductively and mechanically coupled. The semiconductordie 604 includes two separate VCSEL regions, identified in the figure asthe auxiliary VCSEL region 606 and the primary VCSEL region 608. Theseregions are defined physically proximate to one another in order toensure substantially uniform environmental conditions.

The semiconductor die 604, in addition to the auxiliary VCSEL region 606and the primary VCSEL region 608, are enclosed on the substrate 602 by atransparent component enclosure 610. The transparent component enclosure610 includes a lensing region 612 aligned above a central region oremission axis of the primary VCSEL region 608. In many examples, thelensing region 612 may serve as a convex lens, but this is not required.

As a result of this construction, as with other embodiments describedherein, a beam of light emitted from the primary VCSEL region 608 cantraverse the lensing region 612 of the transparent component enclosure610 to illuminate an object 614. As with other embodiments describedherein, a portion of the light radiated/emitted from the primary VCSELregion 608 can reflect from the object 614 and return to the primaryVCSEL region 608 to facilitate self-mixing interferometry detectionand/or measurement of a distance d_(var) (and/or a velocity v) thatseparates an exterior surface of the transparent component enclosure 610from the surface of the object 614.

Conversely, a beam of light emitted from the auxiliary VCSEL region 606does not traverse the lensing region 612 of the transparent componentenclosure 610 and, instead, reflects directly from an interior surfaceof the transparent component enclosure 610 to facilitate self-mixinginterferometry detection and/or measurement of a fixed referencedistance d_(ref). In many embodiments, the transparent componentenclosure 610 can optionally include a reflective region 610 a toincrease the quantity of light reflected back to the auxiliary VCSELregion 606.

In some cases, the reflective region 610 a of the transparent componentenclosure 610 can be formed by depositing a reflective ink or paint ontoan interior or exterior surface of the transparent component enclosure610. In other cases, the reflective region 610 a of the transparentcomponent enclosure 610 can be formed by inserting (e.g., via insertmolding or co-molding) a reflective material such as metal or amultilayer dielectric stack (having high reflectivity) into thetransparent component enclosure 610. In other cases, the reflectiveregion 610 a of the transparent component enclosure 610 can be formed byadhering or otherwise attaching a reflective material such as metal intothe transparent component enclosure 610. In still other cases, thereflective region 610 a of the transparent component enclosure 610 canbe formed by introducing an optical index of refraction mismatch withtransparent component enclosure 610. It may be appreciated that theseexamples are not exhaustive and that other methods of increasingreflectivity of the transparent component enclosure 610 can be suitablefor other embodiments.

As noted with respect to other embodiments described herein,interferometric calculations and/or measurements to cancel or mitigateeffects of temperature and/or other environmental conditions can beperformed in whole or in part by a power controller 616 coupled to theprimary VCSEL region 608 and the auxiliary VCSEL region 606. The powercontroller 616 may be configured in the same manner as described abovein reference to FIG. 4; this description is not repeated.

Still further constructions are possible. For example, FIG. 7 depicts asimplified cross section view of an optical proximity sensor 700, suchas described herein. As with other embodiments described herein, theoptical proximity sensor 700 is formed, at least in part, on a substrate702 to which a semiconductor die 704 can be conductively andmechanically coupled. The semiconductor die 704 includes two separateVCSEL regions, identified in the figure as the auxiliary VCSEL region706 and the primary VCSEL region 708. As with other embodimentsdescribed herein, the auxiliary VCSEL region 706 and the primary VCSELregion 708 are defined and/or disposed physically proximate to oneanother.

The semiconductor die 704 is enclosed on the substrate 702 by atransparent component enclosure 710. Similar to the embodiment depictedin FIG. 5, an optical adapter 712 can be insert molded, or otherwisedisposed into, the transparent component enclosure 710 and aligned abovea central region or emission axis of the primary VCSEL region 708. Asnoted above, the optical adapter 712 may serve as a lens, but this isnot required.

As a result of this construction, and as with other embodimentsdescribed herein, a beam of light emitted from the primary VCSEL region708 can traverse the optical adapter 712 of the transparent componentenclosure 710 to illuminate an object 714. A reflection therefrom canreturn to the primary VCSEL region 708 to facilitate self-mixinginterferometry detection and/or measurement of a distance d_(var)(and/or a velocity v) that separates an exterior surface of thetransparent component enclosure 710 from the surface of the object 714.

Conversely, a beam of light emitted from the auxiliary VCSEL region 706does not traverse the optical adapter 712 of the transparent componentenclosure 710 and, instead, reflects directly from an exterior surfaceof the transparent component enclosure 710 to facilitate self-mixinginterferometry detection and/or measurement of a fixed referencedistance d_(ref). In this embodiment, in contrast to the embodimentshown in FIG. 6, the transparent component enclosure 710 can optionallyinclude a reflective region 710 a to increase the quantity of lightreflected back to the auxiliary VCSEL region 706. The reflective region710 a can be configured and/or coupled to the transparent componentenclosure 710 in the same manner as described above in reference to FIG.6; this description is not repeated.

As noted with respect to other embodiments described herein,interferometric calculations and/or measurements to cancel or mitigateeffects of temperature and/or other environmental conditions can beperformed in whole or in part by a power controller 716 coupled to theprimary VCSEL region 708 and the auxiliary VCSEL region 706. The powercontroller 716 may be configured in the same manner as described abovein reference to FIG. 4; this description is not repeated.

In another example embodiment, FIG. 8 depicts a simplified cross sectionview of an optical proximity sensor 800, such as described herein. Aswith other embodiments described herein, the optical proximity sensor800 is formed, at least in part, on a substrate 802 to which asemiconductor die 804 is conductively and mechanically coupled. Thesemiconductor die 804 includes two separate VCSEL regions, identified inthe figure as the auxiliary VCSEL region 806 and the primary VCSELregion 808. These regions are disposed physically proximate to oneanother.

The semiconductor die 804 is enclosed on the substrate 802 by atransparent component enclosure 810. Similar to the embodiment depictedin FIG. 6, the transparent component enclosure 810 can include a lensingregion 812 aligned with an emission/radiation axis of the primary VCSELregion 808. In this embodiment, the optical proximity sensor 800 can bepositioned behind and/or otherwise coupled to, a transparent substrate814. In one example embodiment, the transparent substrate 814 is a coverglass positioned over a display of an electronic device such as a smartwatch or a cellular phone. In many cases, the optical proximity sensor800 is coupled to the transparent substrate 814 with an optically clearadhesive.

As a result of this construction, a beam of light emitted from theprimary VCSEL region 808 can illuminate an object 816 through thetransparent substrate 814. A reflection therefrom can return to theprimary VCSEL region 808 to facilitate self-mixing interferometrydetection and/or measurement of a distance d_(var) (and/or a velocity v)that separates an exterior surface of the transparent componentenclosure 810 from the surface of the object 816.

Conversely, as with other embodiments described herein, a beam of lightemitted from the auxiliary VCSEL region 806 does not traverse thelensing region 812 of the transparent component enclosure 810 and,instead, reflects directly from an exterior surface of the transparentcomponent enclosure 810 to facilitate self-mixing interferometrydetection and/or measurement of a fixed reference distance d_(ref). Inthis embodiment, in contrast to the embodiment shown in FIG. 6, thetransparent component enclosure 810 can optionally include a reflectiveregion 810 a to increase the quantity of light reflected back to theauxiliary VCSEL region 806. The reflective region 810 a can beconfigured and/or coupled to the transparent component enclosure 810 inthe same manner as described above in reference to FIG. 6; thisdescription is not repeated.

As noted with respect to other embodiments described herein,interferometric calculations and/or measurements to cancel or mitigateeffects of temperature and/or other environmental conditions can beperformed in whole or in part by a power controller 818 coupled to theprimary VCSEL region 808 and the auxiliary VCSEL region 806. The powercontroller 818 may be configured in the same manner as described abovein reference to FIG. 4; this description is not repeated.

Still further embodiments may not require an auxiliary VCSEL region. Forexample, FIG. 9 depicts a simplified cross section view of an opticalproximity sensor 900. The optical proximity sensor 900 includes asubstrate 902 coupled to a semiconductor die 904 defining a primaryVCSEL region 906. The semiconductor die 904 and the primary VCSEL region906 are enclosed against the substrate 902 by a transparent componentenclosure 908 that can, similar to other embodiments described herein,optionally include a lensing region 910. In this example embodiment, apartially-transparent layer 912 is disposed, formed, or otherwisecoupled to an interior surface of the transparent component enclosure908. In this manner, the partially-transparent layer 912 can reflect aportion of light emitted/radiated from the primary VCSEL region 906 backto the primary VCSEL region 906. In addition, the partially-transparentlayer 912 can transmit a portion of light emitted/radiated from theprimary VCSEL region 906 toward an object 914.

As a result of this construction, a beam of light emitted from theprimary VCSEL region 906 can illuminate the object 914 through thepartially-transparent layer 912. As with other embodiments describedherein, a reflection from the object 914 can return to the primary VCSELregion 906 to facilitate self-mixing interferometry detection and/ormeasurement of a distance d_(var) (and/or a velocity v) that separatesan exterior surface of the transparent component enclosure 908 from thesurface of the object 914.

In addition, the portion of light reflected from thepartially-transparent layer 912 facilitates self-mixing interferometrydetection and/or measurement of the fixed reference distance d_(ref).

As noted with respect to other embodiments described herein,interferometric calculations and/or measurements to cancel or mitigateeffects of temperature and/or other environmental conditions can beperformed in whole or in part by a power controller 916 coupled to theprimary VCSEL region 906. The power controller 916 may be configured inthe same manner as described above in reference to FIG. 4; thisdescription is not repeated.

In still further embodiments, a partially-transparent layer may not berequired. For example, FIG. 10 depicts an optical proximity sensor 1000,such as described herein. In this example, a substrate 1002 is coupledto a semiconductor die 1004 that defines a primary VCSEL region 1006. Inthis example, however, a component enclosure 1008 can be formed togetherwith an optical adapter 1010 that can, optionally, perform one or morelensing functions. The component enclosure 1008 also includes a shelf1012 that at least partially blocks (e.g., reflects) light emitted fromthe primary VCSEL region 1006. In this manner, interferometriccalculations and/or measurements to cancel or mitigate effects oftemperature and/or other environmental conditions and to determine adistance to and/or a velocity of an object 1014 can be performed inwhole or in part by a power controller 1016 coupled to the primary VCSELregion 1006.

The foregoing embodiment depicted in FIGS. 5-10 and the variousalternatives thereof and variations thereto are presented, generally,for purposes of explanation, and to facilitate an understanding ofvarious possible constructions of an optical proximity sensor, such asdescribed herein. However, it will be apparent to one skilled in the artthat some of the specific details presented herein may not be requiredin order to practice a particular described embodiment, or an equivalentthereof.

Thus, it is understood that the foregoing and following descriptions ofspecific embodiments are presented for the limited purposes ofillustration and description. These descriptions are not targeted to beexhaustive or to limit the disclosure to the precise forms recitedherein. To the contrary, it will be apparent to one of ordinary skill inthe art that many modifications and variations are possible in view ofthe above teachings.

FIG. 11 is a flowchart depicting example operations of a method ofoperating a proximity sensor, such as described herein. The method 1100includes operation 1102 in which a current or power waveform of a VCSELis monitored. This method operation can be performed in whole or in partby a power controller or a processor such as described herein. Themethod 1100 further includes operation 1104 in which a target propertyis determined based on the monitored waveform of operation 1102. Exampletarget properties include distance, velocity, and/or acceleration. Infurther examples, target properties can include one or more calculatedquantities such as a change in distance over time, a direction ormagnitude of velocity, and/or a magnitude of force applied to a surfaceto cause that surface to deflect or deform by a particular distance. Themethod 1100 further includes operation 1106 in which a target propertyvalue is updated in response to a change in the monitored waveform ofoperation 1102.

FIG. 12 is a flowchart depicting example operations of a method ofoperating a proximity sensor, such as described herein. The method 1200includes operation 1202 in which frequency content of an output signal(e.g., of a photodiode optically coupled to a VCSEL such as describedherein) is monitored. Next, at operation 1204, distance and/or velocityinformation can be determined based on the monitored frequency contentof operation 1202.

One may appreciate that, although many embodiments are disclosed above,the operations and steps presented with respect to methods andtechniques described herein are meant as exemplary and accordingly arenot exhaustive. One may further appreciate that alternate step order orfewer or additional operations may be required or desired for particularembodiments.

Although the disclosure above is described in terms of various exemplaryembodiments and implementations, it should be understood that thevarious features, aspects, and functionality described in one or more ofthe individual embodiments are not limited in their applicability to theparticular embodiment with which they are described, but instead can beapplied, alone or in various combinations, to one or more of the someembodiments of the invention, whether or not such embodiments aredescribed and whether or not such features are presented as being a partof a described embodiment. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments but are instead defined by the claims herein presented.

What is claimed is:
 1. An optical proximity sensor comprising: anenclosure defining an aperture; a primary VCSEL within the enclosure andoriented to emit a first beam of light through the aperture; anauxiliary VCSEL within the enclosure and oriented to emit a second beamof light toward an internal surface of the enclosure; and a powercontroller configured to: monitor a power output of the primary VCSELlight source and the auxiliary VCSEL light source; determine a distanceto an object based, at least in part, on the power output of the primaryVCSEL; and modify the determined distance to the object based, at leastin part, on the power output of the auxiliary VCSEL.
 2. The opticalproximity sensor of claim 1, wherein the power controller is configuredto monitor the power output of the primary VCSEL for self-mixinginterference effects.
 3. The optical proximity sensor of claim 1,wherein the power controller is configured to drive each of the firstVCSEL light source and the auxiliary VCSEL light source.
 4. The opticalproximity sensor of claim 1, wherein the power controller is configuredto drive each of the first VCSEL light source and the auxiliary VCSELlight source with a triangular current waveform.
 5. The opticalproximity sensor of claim 1, wherein the power controller is configuredto determine a velocity of the object based, at least in part, on thepower output of the primary VCSEL.
 6. The optical proximity sensor ofclaim 1, wherein the auxiliary VCSEL is disposed adjacent to the primaryVCSEL such that the primary VCSEL and the auxiliary VCSEL experiencesubstantially the same thermal environment.
 7. The optical proximitysensor of claim 1, further comprising a transparent optical adapterdisposed within the aperture.
 8. The optical proximity sensor of claim7, wherein the optical adapter comprises a lens.
 9. The opticalproximity sensor of claim 7, wherein the enclosure is formed from anopaque material.
 10. An optical proximity sensor comprising: a primarylight source oriented to emit a first coherent beam of light in a firstdirection; a first photodiode optically coupled to the primary lightsource; an auxiliary light source adjacent to the primary light sourceand oriented to emit a second coherent beam of light in a seconddirection toward a reflective surface separated from the auxiliary lightsource by a fixed distance; a second photodiode optically coupled to theauxiliary light source; and a power controller configured to: monitor apower output of the first photodiode and the second photodiode;determine a property of an object reflecting the first beam of lightbased, at least in part, on power output of the first photodiode; andmodify the determined property based, at least in part, on power outputof the second photodiode.
 11. The optical proximity sensor of claim 10,wherein the property is one of distance, velocity, or acceleration. 12.The optical proximity sensor of claim 10, wherein the reflective surfaceis formed from at least one of a metal material or a multilayerdielectric stack.
 13. The optical proximity sensor of claim 10, whereinthe object is an interior surface of a housing of an electronic device.14. A method of determining distance between an object and an electronicdevice, the method comprising: emitting, from a first light source in anoptical proximity sensor, a first coherent beam of light toward theobject; emitting, from a second light source in the optical proximitysensor, a second coherent beam of light toward a surface that isinterior to the electronic device; monitoring power output of the firstlight source and the second light source for self-mixing interferenceeffects; determining a first distance measurement to the object based onself-mixing interference effects of the first light source; determininga second distance measurement to the surface based on self-mixinginterference effects of the second light source; and modifying the firstdistance measurement based on the second distance measurement.
 15. Themethod of claim 14, wherein a distance separating the second lightsource from the surface is a fixed distance.
 16. The method of claim 15,further comprising modifying the first distance based on the seconddistance measurement and the fixed distance measurement.
 17. The methodof claim 14, wherein each of the first light source and the second lightsource is a VCSEL light source.
 18. The method of claim 14, furthercomprising driving the first light source and the second light sourcewith a triangular current waveform.
 19. The method of claim 14, furthercomprising: determining a velocity of the object based on self-mixinginterference effects of the first light source; and modifying thevelocity based, at least in part, on the second distance measurement.20. The method of claim 14, wherein monitoring power output of the firstlight source and the second light source for self-mixing interferenceeffects comprises monitoring power output by a first photodiodeoptically coupled to the first light source and monitoring power outputby a second photodiode optically coupled to the second light source.